NAME

sys/uio.h - definitions for vector I/O operations

SYNOPSIS

#include<sys/uio.h>

DESCRIPTION

The <sys/uio.h> header shall define the iovec structure that includes
at least the following members:
void*iov_base Base address of a memory region for input or output.
size_tiov_len The size of the memory pointed to by iov_base.
The <sys/uio.h> header uses the iovec structure for scatter/gather I/O.
The ssize_t and size_t types shall be defined as described in
<sys/types.h>.
The following shall be declared as functions and may also be defined as
macros. Function prototypes shall be provided.
ssize_treadv(int,conststructiovec*,int);ssize_twritev(int,conststructiovec*,int);Thefollowingsectionsareinformative.

APPLICATIONUSAGE

The implementation can put a limit on the number of scatter/gather
elements which can be processed in one call. The symbol {IOV_MAX}
defined in <limits.h> should always be used to learn about the limits
instead of assuming a fixed value.

RATIONALE

Traditionally, the maximum number of scatter/gather elements the system
can process in one call were described by the symbolic value
{UIO_MAXIOV}. In IEEE Std 1003.1-2001 this value is replaced by the
constant {IOV_MAX} which can be found in <limits.h>.

FUTUREDIRECTIONS

None.

SEEALSO

COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .